Engineer from the Netherlands. Projects in 3D printing, electronics, prop making, sewing and whatever interests me. (If you have a pressing question go to my site and ask it there. I am way more likely to answer it there.)

In this type of sensor the fluid is not allowed to touch any conductor. The conductors should be pretty close together, but it is not the goal to have as little fluid as possible in there. It is allowed to have a gap of a centimeter or over. Temperature should influence the reading a lot and needs to be compensated, but I have not used the sensor much since the project I was going to use this one ended up not happening.

If you want something that keeps time over a longer time you would need something like a stepper motor anyway. If you take a stepper and maybe add some extra gears you'd have the clock you wanted. If you are already making a clock you could also take the hour gear and use it as an input for the orrery (with the right gearing to make the orrery move to the hours).I do like the idea of a combined orrery and clock. I might try that one if I have more time.

Not monitored often, but monitored.5V/2A is USB power supply. That will not be enough for this. There is a beefy 5V power supply in there to make the servo's run. How much current I do not know anymore.

Bearings should be within a few thousands of a millimeter accurate. The problem is most likely in the shafts. Depending on the type and brand, they might nog be 8mm at most, but just roughly 8mm. If your shafts are 8.05mm, you already will not be able to move the bearings on the shaft. I got accurate brass tubing for mine, and I have never had this problem, but it is possible.One way you could try to fix it is use sandpaper on the shaft to get a few hundreds of a millimeter of the tube. You you have calipers you can see how much the tubes are out of dimension.

I seem to remember that freezing temperatures are dangerous in a heat exchanger. It does indeed clog up with ice if you have it. From what I have heard in the case of frost is that people put big underground channels to preheat the air to just above freezing. Filtering is always a good idea on both sides. You'd be surprised how much dust is in the air for an exchanger to accumulate.

Hello Vlad,I have seen your progress, even though I have not really found much time to answer.Your tests looks amazing. I had hoped to test myself last winter but I sadly did not have the time. I wanted to make a proper massflow meter so I can do true efficiency testing. Your results seem almost too good to be true. I can understand that you are skeptical. The basic design does have a lot of surface area, so it is not out of the question. One important thing to look at is not just the temperature in, but also the humidity. If you want to make sure the numbers make sense, get all 4 temperatures and humidifies, 2 at each end. From these values you (or I) can derive the efficiency and unbalance of the exchanger.Good luck. I can't wait to see more.

The moon ring is one of the more fragile parts but I have not ever felt like it would break. The main argument would be that it is a really complicated part to install.In principle the orrery should also work upside down but at this point I do not know if all axes will remain in place with the orrery upside down, but they can be secured in place.It would be an amazing lamp. Bear in mind that the feet will need to be glued in place or replaced is mounted upside down.

Not exactly lying around, but I do have them yes. The module on most of the gears is 1. The big ring and the tiny gear on the moon have a module of 1.25 to make the scale work out. If you need anything more let me know.

The Uno has several pins that match with the schematic in step 10. These are the pins that you can connect to the Uno. These pins are A5, A4, D7 and D8. Also you will need to connect the 5V and the ground. The crystal and programming header are on a normal uno, so you won't need to add those.

When I saw the first pictures, I did not imagine this thing to be made of paper. It looks like it is made from something more like wood. I never thought of this way to make stuff by hand. It may take time, but the end result is amazing and can be made by without any special tools. There is a 3D printing technique like it called LOM, if you are ever interested to see.If you are worried at it's strength, there might be something you could try especially with paper. You could try and impregnate the paper with a watery super glue (CA). I used it myself to impregnate gypsum parts to make them stronger. The super glue should soak into any paper part and set within an hour. After that, the part should be an order of magnitude stronger. In the Netherlands there is "Bison seconde lijm"...

When I saw the first pictures, I did not imagine this thing to be made of paper. It looks like it is made from something more like wood. I never thought of this way to make stuff by hand. It may take time, but the end result is amazing and can be made by without any special tools. There is a 3D printing technique like it called LOM, if you are ever interested to see.If you are worried at it's strength, there might be something you could try especially with paper. You could try and impregnate the paper with a watery super glue (CA). I used it myself to impregnate gypsum parts to make them stronger. The super glue should soak into any paper part and set within an hour. After that, the part should be an order of magnitude stronger. In the Netherlands there is "Bison seconde lijm" which is really strong and works well for gypsum. You can get it in any home improvement store there. But beware to do it in a ventilated area without breathing the fumes. CA fumes are quite nasty. I know this from experience.

Well it is mostly 2 normal sized servo's and 2 micro sized servo's, a few led's and a laser diode. I also used a joystick module. All of those don't have to be expensive. You can get decent servo's for 5 euros each. All other parts mentioned are under 1-2 euros.

I don't do thingiverse anymore. Short version is that I lost all of my goodwill toward Stratasys and Makerbot, and stopped using it.

That is a problem I did not solve. The 'easiest' way of doing it would be assembling the planets as it is right now, but sadly you cannot slide the planets in their current position.

I don't think I myself could make this a kit for an interesting price. I charge somewhere between 5 and 10 euros per hour for 3D printing, and printing takes at least 10 hours. Other materials come to roughly 20-30 euros. Think around 100 euros, but that is from the top of my head.Classroom might be a bit challenging, but die-hard hobbyist should be fine.

I would like to have made it with the right scale and distance planets, but I am afraid that both my 3D printer AND my house are not big enough for that. Even with the examples I have seen I myself have a hard time grasping just what the scale really is.

You can upscale any model before slicing, but there are bearing holes and shaft bores that need to be more or less what they are now. If you want to scale it up much (think more than 5%) you will need to modify the parts so that they themselves are bigger but the bores and bearing holes aren't.I still have the source files available and can share them if you have solidworks. I can share Step files if you have a program that can handle them. If you don't have this software and still need it up-scaled, I might be able to do it, but it might take a while.

I made the paper template. It provides more accuracy than the orrery requires. I tried making a pipe bender but after I discovered 3mm pipe can still be bent by hand without collapsing I ditched the idea.

Making one out of legos is way more complicated than 3D printing one. Lego gives less options for the used gears. You have my respect. I too did the gears by hand first, but that took forever and at some point I was completely done with it. The excel sheet is not perfect but it only took me an hour, so it was totally worth it.

I did consider painting the planets but getting them to look good would have been difficult with my tools. Instead I printed the planets in Bronzefill and polished them. This gives a different look, one that I am quite pleased with.I am curious to see what you will come up with. If you need any more information you can always ask.

Hardware wise not much. Both are powder and inkjet printers, both use the HP C6602A and both are decent, but more there to prove a point an be useful as a stepping stone. Both are at this point no longer supported.If you want to start a 3D thing as a hobby, I advice against powder. It is difficult, messy and has very limited uses. Start with FDM or DLP.